Sound gate



APril 1935- J. c. STEWART 1,997,088

SOUND GATE Filed March 5, 1951 I r- A INVENTOR 0! J16. STEW T BY W ATTORNEY Patented Apr. 9, 1935 r I I t v i r I I 'umTEofsT Es PATENT OFFICE- SOUND GATE,

James G. Stewart, Los Angeles, Calif., assignor to Radio Corporation of America,a corporation of Delaware Application March 5, 1931, Serial No. 520,289

27 Claims. (01. 179-1003 s 'In a talking motion picture projector, the film against the shoe member and the tensionupon is .moved in anintermittent 'manner past a the film is solely that exerted by the leaves of the picture gate, and in a continuous manner past sound gate shoe spring.

a sound gate. Atthe former point the image of 'Having thus briefly described my invention,

' the film, during the period when it is stationary, attention is .now invited to the accompanying 5 isfocused upon the screen to produce the optical drawing in which; eifectof the talking motion picture and at the Fig. 1 is a general side view of my improved sound gate the moving image of the sound portion sound gate; 4 of the combined talking motion picture film is .Fig. *2 is a front view of my gate with the gate thrown upon and used to vary the electrical char'- member removed;

acteristics of a photoelectric device. Such vari- Fig.3 is a cross section ofmy sound gate taken ations cause, by means of suitable amplification on the line 3-3 of'Fig. 1; 1 apparatus, the operation ofthe loudspeakers and Fig. 4 is a front view of the removable sound produce the sound effect of the talking motion gate member; and,

' picture. Fig.5 is a view of the removable gate member 15 The present invention relates to a sound gate looking from the bottom,.thereof, as shown in construction for a talking motion picture pro- Fig. 4. This view also shows'the method of gate jector. The gate of my'invention may be arfmember upon the gate member carrier. ranged to be added to the existing motion picture Attention is now particularly invited to the 2r) projector in the form of an adapter, or the gate drawing in which like reference numerals rep-' may be incorporated in the usual talking motion resent: like parts. The frame member H inpictureprojector. cludes a flange portion 13 at one end thereof, as It is the object of my invention to produce an shown more particularly in Fig. 3, and at improved sound motion picture projector. the other end, a flange l5 (Fig. 2) adapted to It i's'a'further object of my invention to produce carry the gate shoe l1, attached thereto in any 25 an improved sound gate for a talking motion pic'- suitable manner, and afilm roller l920. The tu-reprojector or for a sound reproducing adapter film roller comprises two portions which are for a motion picture projector. spring pressed toward each other. The portion A still further object of my-invention is to proof the roller I9 toward the side of the film bearduce a sound gate which will serve to accurately ing the sound strip is accurately positioned and 30 position the film during reproduction of the sound is secured to the roller shaft which latter is portions thereof. pivoted for'free rotation, as shown more par- A yet furtherobject of my invention is to pro-' ticularly in Fig. 2. The other portion 20 of theduce'a sound gate which will hold the film under roller is spring pressed toward the portion [9 by 35.. an'even tension and yet permit it to move freely means of the spring 22 which surrounds the roller past the sound reproducing point. shaft. The film roller shaft is pivotedin the Another object of my invention is to produce portion-l5 of the frame H in any suitablemanan apparatus which will place the film at the ner, the details of which are clearly shown in sound reproducing point underan even tension, Fig. 2 but constitute no part of the present 40 yet permit its free motion thereby and at the invention.

same time accurately positioning the film at said The portion I3 of the frame H has mounted point. a thereon two pins 2l2l, suitably mounted upon These and other objects of my invention will which is the film gate member carrier 23. This become apparent from the following specification rri r is spring pressed by means f springs taken in connection with the appended drawing. 25 surrounding the pins 2|. In order to main- 45 In accomplishing the objects of my invention, tain the gate'in the open position there is provided I providela single spring member comprising two a pin 21 likewise mounted in the member [3, said' leaves adapted to press upon the opposite sidesof pin having an annular recess 3| near the end the film as it moves past the soundreproducing thereof in which a latch member 29 is adapted 50. point. 'I provide a film shoe in the form of an to fall when the gate is in the open position.

are against which shoe it is pressed by the two This serves to retain the gate open against the leaves of the spring. The spring is carried in a pressure of the springs 25. The removable gate. removable gate member which is spring pressed member 35 has an arcuate surface corresponding against the shoe member. Small spacing pins are in curvature to the arcuate surface of the shoe provided,however,'in the gate member which rest' member l1. Slots 4l-4l and 43-43 .arei'cut 56; f

provided a hole 45 through which the reproducing light is permitted to pass to or from the sound portion of the film passing the film gate. Eachof the leaves 3933 of the spring 31 has a cutaway portion 41 on its inside in order to permit areversing of the spring and yet prevent interference with the sound record at the reproducing point.

When the gate is closed; the pressure of the springs against the gate carrier member 23 forces the gate member toward the shoe 11. until the ends of the studs 49-49' carried by the gate member 35 bear against the surface-of the shoe member H. The film, however, is not of sufli cient. width to be in any way affected 'bythis pressure. In other words; the. film. passes be tween the studs 49 -49 and is pressed. by means ,of the spring leaves 39 againstlthe. arcuate surface of shoe l1; r r a As before noted ,thegate'member' 35 is removably mounted to permit adjustment of the spring 31 or replacementthereofjas may be desired. In accomplishing this, there isattached to the gate member atzthe rear thereof a member 55. At one end of the member jis provided a projection 6 l l which fits into a recess under. the tongue 59 left in the carrier member, 23 when'the portion 51 is cut away. The member. 55 is provided with a lug portion 63 which bears: against the surface 55.4

of the cutaway portion 51 of carrier 23; Thus when the member 55 is pressedagainst the-sur face of 69, as shown in Figs. 3 and '5, the pressure of 63 againstlfiilocks theprojectionllil under the projection-'59. The'gate member. is main tained in this position by means of the spring 61 secured to the member 55by means ofscrewsifi.

This spring partially surrounds the reduced'portion 690i carrier-23.

In thev operation of my invention, the gate memberiis placed on the carrier member while thelatter is in the. position shown in. Fig. 1,'that is, initheopen position. The film is passed through the gate roughly in theposition shown;

by the section line 3.3, and the. latch 29 is'released permitting the carrier member 23 to move 'tothe running position. This forces the studs- 49-'-49:of the gate member .35 against the surface ofishoemember I! and the film between the 'sur.. faces of the roller B. ,It' is toibe noted that the position of the film isgovernedby the rollers-l9. as the gate moves into the running position." Thus. the film islaterally positioned before the spring leaves 39 bearfon it. 'As the gate'iscompletely closed, theleaves .39 press the film against the cm'vedsurface of the shoe l1.

'It'can-be seen thus that thereis exerted upon thefilm'a light, even pressure which will serve toikeep the. film at all-times pressed against the curved surface of shoe l1 and thus in exactfocu's relative. to the sound reproducing optical system; The roller I920 serves to accurately position the film laterallyas. above described in order that" I the illumination may be arranged tobe confined surface of said gatemember::tobear againstthe surface of said shoemember andthusaccurately: position said gate member relative thereto, :Iand; 1c

toathe'soundportion of thefilm. 7

'Any appropriate means maybe provided for mounting the gate apparatus with. the projector,

The leaves 39 bear uponthe bottom of.

the specific details of which mounting constitute no part ofthe present invention. 7

Having thus described my invention, it is to be understood that various changesmay be made therein, and that I am therefore not to be limited to the specific embodiment shown and described for the purpose of illustration only, but by the actual scope of my invention as, set. forth in the appended claims. I i

I claim:

1. A sound gate comprising a frame member, a shoe member carried by said frame member, having a curved surface over which a fllm is adapted to pass, a roller member for cooperation with the film. also carried thereby, said roller comprising one portion laterally fixedand a second spring pressed portion adapted to press the film passing through said roller against the fixed portion thereof to accurately position said film laterally, a spring pressed gate carrier member, a gate member carried by said carrier member and having a curved surfaceadapted to cooperate with thecurved surface of said shoe member,

positioning studs disposed onsaid gatemember; to bear against the surface of. said shoemember and-thus accurately position said gate member relative thereto, a springmember carriedby said gate member, saidspringmember comprisingtwo leaves for bearing upon the marginal. portions of the film and pressing, it into contact with.

said shoe, cutaway portions on'the' inner sides; of each of said leaves, and a removable mountingfor said gate member'whereby it upon said gate carrier member 2. A sound gate comprising a frame member,

is mounted a shoe member carried by said frame member,

having a curved, surface over which a; film is adapted to pass, a roller member for cooperation V laterally, a spring pressed gate carrier member, movable to operating and threading positions,

means for retaining said. member-in the thread- 'ing position, a gate member carried-by said car-.

rier member and having acurved surface adapted, to cooperate with the curved'su'rface of said member, positioning studs disposedon saidfgate mem-' ber to bear'against the surface of said shoe;mem,--

ber and thus accurately position said gateimemr ber relative thereto, a. carried by said gate member, saidispring member come.

prising twoleaves for. bearin s he.marginalv portions of the film andpressingit; into contact;

with said shoe; cutaway portions of eachfiide, of

said leaves and a; removable mounting; for said;

gate member whereby it is mountedjuponrsaid gate carrier member;

3. A sound gate comprising aframe memberi a shoe member carried by said frame member and;

having a curved surface over whicha film, is

adapted to. pass, amlle'r member-for cooperation, with the'film. and-salsa carried thereby, said. m ter comprising one portion memo fl-Xedanda second spring pressedportion adaptedito prcss the;

film passing through saidroller; against said fixed; portion thereof to accurately position. said film laterally.. a spr n pressed carnen member, a removably mounted gate member carried by said carrier member, positioning studsdisposedinathe a spring membercarried by said gate member for pressing the film into contact with said shoe;

4. A sound gate comprising a frame membena shoe member carriedb'y said frame member and having a curved surface over which a film is adapted to pass, a roller member for cooperation with the film also carried thereby,-said roller ,comprising twoportionsone portion'of'which is laterally fixed-and the second'iof which. isuspring pressed and adapted to'press the film passing through said roller against. said fixed' portion thereof to accurately position said film laterally, a spring pressed carrier membermovable. to .operating and threading positionsgmeans'for 1'61- taining said member in threadingnposition, a removably mounted gate member carried by said carrier member, positioning studs-"disposed in the face of said gate member to-bear-against the surface of said shoe member,jand thus accurate ly position said gate member relative thereto, and a spring member carried by,saidf,gate member for pressing the film into contact with said shoe.

5. A sound gate comprising a frame member, a shoe member carried by saidframe member and having a curved surface over which a-film is adapted to pass, a roller member for cooperation with the film carried thereby, said roller comprising one portion laterally fixed and a second spring pressed portionadapted to press the portion passing through said roller against said fixed portion thereof to accurately position saidfilm laterally, a spring pressed carrier member movable to operating and threading positions,'means for retaining said member in the threading position, a removably mounted gate member carried by said carrier member, positioning studs disposed in the surface of said gate member to bear against the surface of said shoe member and thus accurately position said gate, member relative thereto, and a spring member carried by said gate member, said spring member comprising two leaves for bearing upon'the marginal portions of the film and pressing it into contact'with said shoe.

6. A sound gate comprising a frame member, a shoe member carried by said frame member and having a curved surface over'which a film is adapted to pass, a roller member for cooperation with the film carried thereby, said roller com-' prising one portion laterally fixed and a second spring pressed portion adapted to press the portion passing through said roller against said fixed portion thereof to accurately position saidfilm' laterally, a removably mounted gate member carried by said carrier member, positioning studs disposed in the surface of said gate member to bear against the surface of said shoe member and thus accurately position said gate member relative thereto, and a spring carried by said gate member, and said spring comprising two leaves for bearing upon the marginal portions of the film and pressing it into contact with said shoe.

'7. A sound gate comprising a frame member, a shoe member carried by said frame member and having a curved surface over which a film is adapted to pass, a spring pressed carrier member movable to operating and threading positions,means for retaining said carrier member in the threading position, a removably mounted gate member carried by said carrier member, positioning studs disposed in the surface of said gate member to bear against the surface of said shoe member and thus accurately position said gate member relative thereto, and a spring member carried by said gate member for pressingthe film into contact with said shoe.j

.8. A sound gate comprising. a frame member, a shoe member carried by said frame member and having a curved surface over which a film is t to, and a spring member carried .bysaid gate member and comprising two leaves for bearing upon the marginal portions of the film and pressing it into contact with said shoe.

9. A sound gate comprising .a frame member, a shoe member carried by said-frame member and having a curved surface over which a film is adapted to pass, a spring pressed carrier member movable to operating and threading positions, means for retaining said-carrier member inthe threading position,'a removably mounted gate member carried by said-carrier member, and a spring member carried by saidgate member comprising a plurality of leaves for bearing'upon the marginal portions of the film and pressingslt into contact with said shoe. v I 10. A sound gate comprising a frame member, a shoe member carried by said frame member and having a curved surface over which a film is adaptedjto' pass, a spring pressed carrier member movable to operating and threading positions, means for retaining said carrier member in the threading position, a. removably mounted gate. member carried by said carrier member, and a spring, member carried by said gate member for pressing the film into contact withsaid shoe;

11. A sound gate comprising a frame member,

a shoe member having a curved surfacerat the 7 sound translation point over which a film is adapted to pass, said member being carried by said frame member, a spring pressed carrier member, a removably mounted gate member carried by said carrier member, and a flexible spring member carried by said gate member for pressing the film into contactwith the curved surface of said shoe.

12. A sound gate comprisinga frame member, a shoe member over which a film isadapted to pass, said shoe member being carried by said frame member, a spring pressed; carrier member, a removably mounted gate member carried by said carrier member, and a fiexible member carried by said gate member and arranged to engage said film for pressing it into contact with said shoe.

13. A sound gate comprising a frame member carrying a shoe member having a surface over which a film is adapted to pass, a spring pressed carrier member, a removably mounted gate member carried by said carrier member, means forlimiting the motion of said gate member toward said shoe member, and a light flexible spring member carried by said gate member and arranged to engage said film for pressing it into contact with said shoe. v

14. A sound gate comprising a frame member, a shoe member carried by said frame member, and having a surface over which a film is adapted to pass, a spring pressed gate member, means for limiting the motion of said gate member toward said shoe member, and a fiat spring carried by said gate member adapted to engage said film and press it into contact with. said shoe.

15. A sound gate comprising a shoe'member having a surface over which a film is adapted to pass, a spring pressed gate'member adapted to V presstoward said shoe member, means for limiting the motion of said gate member toward said shoe member, and a light leaf spring member adapted to engage said filmiand press it into contact with said shoe member.

16; A sound gate comprising a shoe member having a curved surface over which a film is 2 adapted to pass at the sound translation point,

a spring pressed gate member opposed to said shoe member, means for limiting the motion of said gate member toward said shoe member,

and a plurality ofv light fiat spring members en- 1 gaging the filmkfor positioning the film accurately'as it passes between said gate member and said shoe,

17. A sound gate comprising aicurved 'shoe member over which the film being reproduced is adapted to bepassed, a spring pressed gate member movable to operating and threading po" sitions; means for retaining said gate member inthe threading position, means for limitingthe nrotion. of said gate member toward said shoe member, and a-fiexible member adapted to engage said film and press it against said shoe r member.

' 18. A sound gate comprising a shoemember having a surface over which the film being reproducedis adapted to pass, a spring'pressed car-' rier member, a removably'mounted gate member carried by said carrier member, means for limitd a ing the motion of said gate member toward said shoe, and a flexible member for engaging said film: and pressing itinto contact with said shoe.

f :19. A sound gate comprising a curved shoe member having a curved surface over which the film being reproduced is adapted to pass at the sound translation point, a' spring pressed gate adapted to cooperate with said shoe membenan'd carried by the: gate and contacting with said shoe for limiting the motion of said gate member toward said shoe. j V

'20. A sound gate comprising a shoe member over which the film being reproduced is adapted to pass, a gate member adapted to cooperate with said shoe member, and a flexible member carried by said gatemember for engaging said film andpressing it into contact with said shoe;

2 1. 'A. sound gate comprising a curved film shoe member provided with anaperture, a gate memmemes ber' arranged to cooperate with saidshoemember;v and: a fieidble member supported by said gatemember and, arranged to press: the'film into contact with said shoe" at said aperture with a pressure" which iii-greatest at the sound translating point and: decreases in opposite directionslthere member provided with an aperture, agate mem her arranged to cooperate, with saidshoe Jmembur, aiflexrble member supported by saidv gate member and topressa'tne mm into contact with said: shoeat slidaperture with a pressure which is greatest at the point of sound translation, and resilient meansfor biasing said gate member toward: said: shoe l 23. A. sound gateeomprising a curved film'sho'e member providedwith'an aperture, a gate mem;

ber armngedto' eooporate with said shoemembane flenblemember sopported'hy said gate andanrangedto press the film into con tact with said shoe at saldapertur'e with a pres-- surewhicl'i is greai'estot the point of sound translation, resilient'means tor biasing said gate member' toward said slide member, and means for 22.x was eumpriamg a curved film shoe limiting the movement of said gate member to ward saidishoe memben,

'24. A i'il'm; gate comprising a; curved stationary member and for hO1dillg 'a film'the1e against comprising a fiat-spring member of aninverted U shape; and means for supporting said springmember adjacent its ends only.

251- A- film gate comprising a curved stationary" member and: a movable member'holding a film thereagainst comprising a spring member 01;

an, inverted U shape, and a movable member sup-[ said spring member adjacent its ends 

